1. Field of the Invention
Embodiments of the invention relate to the field of semiconductor, and more specifically, to semiconductor fabrication.
2. Description of Related Art
During the fabrication process of semiconductor devices, the active dice are subject to a number of mechanical and thermal stresses that may cause failures. For example, in the wafer dicing and accelerated test phases, the saw-induced or thermo-mechanical stress-induced cracks may propagate into the active circuitry and cause reliability failures under temperature and/or humidity exposure.
Existing techniques to avoid these reliability failures have a number of drawbacks. Typical techniques use a metal guard ring together with a nitride passivation on top of the metallization stack to create a hermetic seal around the active die. The hermetic seal is intended to prevent cracks from propagating into the active circuitry. However, these designs have been shown inadequate. Cracks have been observed propagating over the top metal layer of the guard ring. As a result, the hermetic seal is breached and moisture is able to penetrate into the die. Corrosion and/or metal migration eventually lead to failures during accelerated reliability testing.